Isocyanates of hydrolyzed ethylene vinyl ester interpolymers



Patented Oct. 19, 1948 ISOCYANATES OF HYDROLYZED ETHYLENE VINYL ESTERINTERPOL YMERS Donald John Loder, Wilmington, DeL, assignor to E. I. duPont de Nemours & Company, Wilmington, Del., a corporation of DelawareNo Drawing. Application February 4, 1944,

'Serial No. 521,135

28 Claims.

1 This invention relates to a process for the preparation of newrubber-like compositions oi. matter, and more particularly to theirpreparation from an isocyanate, an interpolymer of ethylene and anorganic acid ester or vinyl alcohol.

In the U. S. patentof J. R. Roland, Jr., 2,386,- 347, filed February 13,1945, as a continuation of application S. N. 446,114, filed June 6,1942, there is described a process for the hydrolysis of interpolymersof ethylene and organic acid esters of vinyl alcohol. The process of thepatent is conducted by hydrolyzing the ethylene-organic vinyl esterinterpolymer by dissolving it in a suitable solvent, such as methanol,or ethanol, or in a mixture of an alcohol and a hydrocarbon such astoluene, and then treating the resulting solution with a hydrolyzingagent or catalyst such as an alkali or mineral acid. The processdescribed by Roland likewise includes alcbholysis as well as hydrolysiseither water or alcohol beingemployed' to split the ester groups fromthe interpolymer; in either event the resulting product is substantiallythe same. The products of the Roland patent or similar products obtainedin accord with any suitable process are further treated by the processesof this invention.

An object of the present invention is to provide valuable newcompositions of matter. Another object is to provide a process forconverting partially or completely the hydrolyzed lnterpolymers ofethylene and vinyl esters to new compositions of matter. A furtherobject of the invention is to provide a process for the interaction of ahydrolyzed interpolymer of ethylene and vinyl acetate with an alkyl oraryl ester of isocyanic acid. Yet another object is to provide optimumconditions for conducting such a process. Still another object is toprovide products that can be converted to fibers, films, adhesives, andrubberlike compositions. Other objects and advan-.

tages of the invention will hereinafter appear.

The above objects are realized in accord with the invention bysubjecting to a. reaction with an alkyl or aryl isocyanic acid ester apartially or completely hydrolyzed interpolymer of ethylene and anorganic acid ester of vinyl alcohol, or a similar product produced byany process such, for example, as those processes producing syn theticresins which contain free hydroxyl groups and more particularlysuchresins as the polyvinyl alcohols, polymers obtained from the hydrolyzed lnterpolymers of vinyl acetate and vinyl chloride, polymers ofallyl alcohol, and the like. The reaction may be conducted by dissolvingthe interpolymer and the isocyanate in a suitable mutual solvent, i. e.a solvent for the interpolymer and theisocyanate, and subsequentlyeffecting the reaction between the interpolymer and the isocyanate byheating. The products which are formed, it is believed, by the additionof the isocyanate to the hydroxyl group of the hydrolyzed interpolymermay be called N-alkyl or N-aryl carbamates of the hydrolyzedinterpolymer of ethylene and a, vinyl ester.

The lnterpolymers which may be used in the process oi. this inventioninclude all of the interpolymers of ethylene with organic acid esters ofvinyl alcohol. Specific examples of these interpolymers include thelnterpolymers of ethylene essential to the operability of the processthat all of the ester groups be split from the interpolymer, althoughfor optimum results at least 50% thereof should be removed, and all maybe removed if desired.

The alkyl isocyanates that may be employed include particularly thelower alkyl isocyanates, such for example, as methyl, ethyl, normal andisopropyl, normal and isobutyl, although the higher straight and branchchain alkyl esters as well as the aryl esters of the isocyanic acid mayalso be used such as the phenyl and naphthenyl isocyanates.

The reaction is initiated preferably in the presence of about one moleof the isocyanate per equivalent interpolymer hydroxyl group althoughdesirable products can be obtained with from 0.5 to 5.0 moles of theisocyanate per equivalent of the interpolymer hydroxyl group.

The reaction is conducted between approximately 50 and 200 C., and ispreferably carried out at about C. and 1 atmosphere pressure.

'The reaction, however, may, if desired, be -con-,

ducted under sub-, normalor superatmospheric pressures. particularlycritical, for valuable products having desirable film-forming propertiescan be obtained from reactions extending from in the order of M to 10hours at temperatures in the prox- The duration of the reaction is notilnity or (2. Generally several hours are required ior complete reactionbut it is not necessary th t all the hydroxyl present react. Excellent scan be iormed from resins in which only from to 20% of the hydroxylgroups are converted to N-alkyl carbamate groups.

Various solvents may be employed for effecting the reaction, and thoseselected are preferably mutual solvents for both the interpolymer andthe isocyanate. Examples of such solvents include dioxane,1,8-dioxoianes, formamide and dimethyl formamide.

The products of the reaction are isolated by precipitation from thesolvent, which may be achad a clear amber color, was very tough andstifl, and was hot-drawn from a melt to an extra-tine and very smoothfiber. The tensile strength of a fiber was 4900 lbs. per square inch,with an elongation of 350%, and a recovery to 130%. The resinous productcontained 4.8% nitrogen, which corresponds to about 46% of the hydroxylgroups initially present substituted by N-ethyl carbamate groups.

Example 3.-A reaction vessel was charged with 2 parts of an interpolymerof ethylene and vinyl acetate (in whichthe ratio of ethylene vinylacetate was 1.6:1) 200 parts of dioxane, and 2 parts oi ethylisocyanate. The mixture was complished by the addition of water. Anysoll5 heated on a steam bath while being irradiated vent remaining inthe resin is removed by subwith a mercury zapor H4 lamp, and maintainediecting the precipitate to the action of steam. at a temperature ofapproximately 90 C. for The thus precipitated polymer may be then milledabout minutes. The resulting product was at temperatures between 30 and150 C. in order steam distilled for the removal or the dioxane, torender it dry and homogeneous. precipitated with water and milled for 10min- Examples are given which disclose specific emutes at a temperaturebetween 70 and 80 C. A bodiments of the invention in which proportionsclear, tough, stifl product was obtained, which are by weight unlessotherwise indicated. could be heat-drawn into a very fine fiber. TheExample 1.-A reaction vessel was charged with tensile strength of theproduct was 3350 lbs. per 10 parts of a hydrolyzed interpolymer ofethylene square inch with an elongation of about 400% and and vinylacetate, (in which the ethylene: vinyl a retraction to about 100%.acetate ratio equalled 8:1) together with 10 parts Example4.--A'hydrolyzed ethylene-vinyl aceoi ethyl isoc'yanate and 240 parts ofdioxane. The tate interpolymer having an ethylene vinyl aceresultingmixture was heated on a steam bath to tate ratio of 1.811 was convertedto the N-ethyl a temperature oi'90" C. and under a pressure of carbamateby the method described in Example 2. approximately 1 atmosphere for Vhour. The (11- The resulting resin was pressed into a film at 140 oxanewas removed by steam distillation, and the C. The film prepared in thismanner had a tensile residue precipitated with water, filtered, andsubstrength oi! 6000 lbs. per square inch, with an sequently milled for15 minutes in a rubber mill at elongation of 450%, and a recovery to400%. An 100 C. A clear, very stiff, and tough product was imperfecthand-drawn fiber, prepared by melting obtained, which could be melt-spuninto fine 11- a strip of the film, and drawing the resin while bers. Afilm of this resin prepared by processing molten to 238 denierhad astrength of 1.9 grams a portion of the product between platens at 135per denier. C. had a tensile strength based on original dimen- Theprocess of Example 1 was duplicated in the sions of approximately 3500lbs. per square inch examples illustrated in Table 1 except forcondiwith an elongation of approximately 800%. tions as noted.

Table I Example No 5 6 7 8 9 Ratio E A 1.8.. 2.2. Amt. E A (parts) 10 1o3. Solvent dioxane.-. dinxane. Solvent (parts) 300 100. Ioscyanate(alkyl)... phenyl isobutyl. Ioscyanatc( arts)..- 105 ll 3. Temp. C.-100. Pressure (atms.).... 1. Time (hrs.) 3. Milled min.)........ 15.Milled l-emo, C.) 100. Pro ert es:

enaile (p. a. i.) 2700. Elongation 400. Recovery to 0'7 50.

1 Ethylene-vinyl acetate interpolymer.

The above process was repeated, except that the reaction time wasapproximately 1 hour. In

' this instance a film was obtained having a tensile strength ofapproximately 4350 lbs. per square inch, with an elongation ofapproximately 800%.

which the ethylene vinyl acetate was 2.1:l),

200 parts of dioxane, and 7 parts of ethyl isocyanate. The reaction wasconducted at 90" C. and 1 atmosphere for approximately 5 hours, thedioxand was'removed by steam distillation, and the product then milledfor 20 minutes at a tempera- The interpolymers employed in the aboveexamples were hydrolyzed by treating a benzene solution of theinterpolymer with a methanol solution of sodium hydroxide at atemperature of approximately 30 C. for 4 hours.

The products of the invention can be modified by reaction with aldehydesor 'acetals to give valuable thermosetting resins including elastomersand adhesives which reactions result in the formation of cross linkageswithin the molecule. Such treatments may be carried out, for example, byheating the products prepared above to a temperature. between 20 and 80C. for from about 5 to about 30 minutes in the presence of an amount ofaldehyde or acetal approximately equal, on a stoichiometrical weightbasis, to the ture between 30'and C. The final product 75 N-alkylcarbamate substituents present. Formalin may be used in lieu offormaldehyde which may, if desired, be replaced by methylal,methoxymethoxy ethanol, or the like, the reaction preterably beingcarried out in an alcoholic solution at a pH lower than 7. Uponevaporation of the alcoholic solvent-"a. resinbus product is obtainedhaving excellent adhesive properties. Adhesive bonds formed with thesethermosetting resins may be hardened by heat treatment at temperaturesbetween 100 and 150 C. whereby a water insoluble bond is made that isresistant to both hot and cold water. These thermosetting resins may bemodified if desired by mixture with dimethylol urea, urea-formaldehyderesins, phe-. uni-formaldehyde resins, melamine resins and the like.Ordinarily however the resins obtained by simple treatment withformaldehyde impart adequate strength to bond materials together.

The examples which follow illustrate the type of products obtained bytreating the N-ethyl alkyl or N-aryl carbamates of hydrolyzedinterbetween 30 and 200 C. with an alkyl isocyanate there being presentfrom 0.5 to 50 moles of the alkyl isocyanate per equivalent of hydroxylin the polymer.

2. A process which comprises subjecting a ydrolyzed interpolymer ofethylene and vinyl acetate to a temperature between 30 and 200 C. withethyl isocyanate there being present from 0.5 to 5.0 moles of ethylisocyanate per equivalent of hydroxyl in the interpolymer.-

3. A process which comprises subjecting a hydrolyzer interpolymer ofethylene and vinyl acetate to a. temperature between 30 and 200 C. withmethyl isocyanate there being present from The unmodified products ofthis invention are particularly well adapted to the preparation offilaments or films which can be formed by dry spinning or forming or hotmelt spinning or.

stantially its melting point and drawn into a filament or film at asufilciently rapid rate to give the desired denier or thicknessrespectively. After stretching, and heat setting of the fibers theproperties are improved for many uses.

The products both with and without cross link-. ing agents are likewisesuitable for use in the plastic arts, for the preparation of sheets,molded articles, and other fabricated shapes. These may vary from hardrigid products to soft elastic or soft plastic materials depending onthe nature of the resin employed and the nature and quantity ofpigments, fillers, plasticizers and curing agents added and the curingor molding cycle employed,

The products of this invention afford very useful coating compositionsand unsupported films. They are particularly attractive as coatingagents for fabrics. The films may be used as the suppolymers disclosedabove with cross-linking 0.5 to 5.0 moles of methyl isocyanate perequivagents. alent of hydroxyl in the interpolymer.

' Per Cent E/VA r c t Cum 1* 11 long' 30W 007 or en ens e, 1 0 ExampleRatio N Compounding 100 pts. Polymer plus pts. 3' L Um R M l s cc.

Min mate to- 10 1. 8 2. 2 None so 135 a, 400 325 40 2, 350 2, 050 ll 1.8 2. 2 5 paraiol'maldehyde. 20 135 3, 200 300 30 3, 1, 100 12. 1.8 2. 2pamiormaldehyde. 135 3, 400 270 800 13. 1.8 2. 2' do 135 3,400 250 10.Z. 800 14 1.8 0.7 None 20 w 135 2,750 350 2, 400 1,500 l6 1. 8 6. 7 10paraiormaldchyde 30 135 1, 950 350 25 950 100 15. 1.8 6. 7 20 C, 10paraformaldehyde. 3 135 2, 500 300 50 2, 500 1, 350 i7 1.8 2.35 10paraiorlnaldehyde.-... 3 135 3, 200 50 0 l8 2.1 l.84.... d0 20 135 3,300350 00 1,750 600 19 4. 3 l. 8 i .do 30 135 3,000 410 170 1, 200 600 20..1.7 5.0 .....do 00 135 1,050 200 5 350 21 l. 7 5.0 25 DMU,1 NH|CL. 30135 3,100 25 0 22 1.8 5. l 10 paraiormaldehydo 30 135 2, 700 350 2, 150700 23. 1. 8 5. 1 l0 paralormaldehyde 5 C230. 30 135 2, 400 350 2,050700 24... 1.8 5. 1 l0 pnmiormaldeh de 5 St. 30 135 2, 450 200 25 750 25.1.8 5.1 10 DMU, 1 NH 1 30 135 4,550 18 4.550 26 1.8 5.1 d 15 135 4,100,150 15 2,450 27. l. 0 2.0 10 paraiormaldehyde 30 135 3, 550 385 2. 400l, 100 1. 6 2.0 do h) 2,100 310 75 2, 000 850 29 1. 6 2. 0 10 mothoxymethyl uron, l NHAO] 30 135 2, 100 25 1,300 30 l. 6 2.0 10 his methoxymethyl urea. 1 N H401 .i 60 135 3, 350 200 45 1,450

Examples 10 to 17 and 10 to 30 were N -ethyl carbamate and Example 18N-phenyl carbamate oi E/VA C =-channel black mrbon. St==stearlc acid.

DMU =dimethylol urea.

4. A process which comprises subjecting a hydrolyzed interpolymer ofethylene and vinyl aceate to a temperature between 30 and 200 C. withphenyl isocyanate there being present from 0.5 to 5.0 moles oi phenylisocyanate per equivalent of hydroxyl in the interpolymer.

5. An N-alkyl carbamate of a hydrolyzed interpolymer of ethylene andvinyl acetate.

6. An N-ethyl carbamate 01' a hydrolyzed interpolymer of ethylene andvinyl acetate.

7. An N-phenyl carbamate of a hydrolyzed interpolymer of ethylene andvinyl acetate.

8. An N-methyl carbamate of a hydrolyzed interpolymer of ethylene andvinyl aceta 9. A process which comprises heating an N- alkyl carbamateof a hydrolyzed interpolymer of ethylene and vinyl acetate with acompound selected from the group consisting of formaldehyde, methylol,and methoxy-methoxy ethanol.

10. A process which comprises subjecting N- ethyl carbamate of ahydrolyzed interpolymer of ethylene and vinyl acetate to a. reactionwith ggrmaldehyde at a temperature between 20 and 11. The product inaccord with the process 01' claim 10. e

12. A process for the preparation of an N-sub- 7 stituted carbamate oi ahydrolyzed interpolymer of ethylene and vinyl acetate containing from 1to moles oi ethylene per mole of vinyl acetate, which comprisessubjectingsuch an interpolymer of ethylene and vinyl acetate, which hasbeen hydrolyzed, to a reaction with from 0.5 to 5.0 moles of an alkylisocyanate per mole oi the interpolymer, the reaction being affected ata temperature between and 200 C.

13. A process for thepreparation or an N-substltuted carbamate of ahydrolyzed interpolymer oi ethylene'and vinyl acetate which comprisesheating a hydrolyzed interpolymer of ethylene .8 22. A process whichcomprises subiectinl ethyl isocyanate and a partially hydrolyzedinterpolymer or ethylene and a vinyl ester or an aliphatic saturatedorganic monocarboxyllc acid to a temperature between30 and 200 0., therebeing pres ent from 0.5 to 5.0 moles oi the isocyanate per equivalent ofhydroxyl in the interpolymer.

and vinyl acetate with an alkyl isocyanate, there being present from 0.5to 5.0 moles 01' the alkyl isocyanate per equivalent of hydroxyl in thein+ terpolymer.

14. A process for the preparation of an N-substituted carbamate of ahydrolyzer interpolymer of ethylene and a vinyl ester of an organicmono- 1 cyanate is an aryl isocyanate.

18. The process of claim 14 conducted in a mutual solvent for thehydrolyzed interpolymer and the isocyanate.

19. A process for the preparation or an N-substituted carbamate of ahydrolyzed interpolymer of ethylene and vinyl acetate which comprisesheating a hydrolyzed interpolymer of ethylene and a vinyl acetate with amono ester of monoiso..

,cyanic acid at a. temperature between 30 and 200C.

20. The process of claim 19 in which the isocyanate is an alkylisocyanate.

21. The process of claim 19in which the isocyanate is an arylisocyanate.

23. A process which comprises subjecting methyl isocyanate and apartially hydrolyzed interpolymer .of ethylene and a vinyl ester of analiphatic saturated organic monocarboxylic acid to a temperature between30 and 200 C.

24. A process which comprises subjecting phenyl isocyanate and apartially hydrolyzed in-- terpoiymer of ethylene and a vinyl ester of analiphatic saturated organic monocarboxylic acid to a temperature between30 and 200 C.

25. An N-substituted carbamate oi a hydrolyzed interpolymer of ethyleneand a vinyl ester 01' an organic monocarboxylic acid.

26. A process which comprises subjecting an N- substltuted carbamate ofa hydrolyzed ,interpolymer of ethylene and a vinyl ester of an allphaticsaturated organic monocarboxylic acid to a temperature between 20 and C.with a com-- pound of the group consisting of iormaldehyde, methylal andmethoxymethoxyethanol.

27. A product in accord with the process of claim 26.

28. The product obtained in accord with the process of claim 26 whichproduct is hardened by heating to a temperature between and C.

DONALD JOHN DODER.

nsraanucas crrnn The following references are'of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Dorough Mar. 24, 1942 Number I

